一、实例

#include <stdio.h>
#include <string>             // for STL string class
#include <windows.h>          // for HANDLE
#include <process.h>          // for _beginthread()using namespace std;class ThreadX
{
private:int loopStart;int loopEnd;int dispFrequency;public:string threadName;ThreadX( int startValue, int endValue, int frequency ){loopStart = startValue;loopEnd = endValue;dispFrequency = frequency;}// In C++ you must employ a free (C) function or a static// class member function as the thread entry-point-function.// Furthermore, _beginthreadex() demands that the thread// entry function signature take a single (void*) and returned// an unsigned.static unsigned __stdcall ThreadStaticEntryPoint(void * pThis){ThreadX * pthX = (ThreadX*)pThis;   // the tricky castpthX->ThreadEntryPoint();           // now call the true entry-point-function// A thread terminates automatically if it completes execution,// or it can terminate itself with a call to _endthread().return 1;          // the thread exit code}void ThreadEntryPoint(){// This is the desired entry-point-function but to get// here we have to use a 2 step procedure involving// the ThreadStaticEntryPoint() function.for (int i = loopStart; i <= loopEnd; ++i){if (i % dispFrequency == 0){printf( "%s: i = %d\n", threadName.c_str(), i );}}printf( "%s thread terminating\n", threadName.c_str() );}
};int main()
{// All processes get a primary thread automatically. This primary// thread can generate additional threads.  In this program the// primary thread creates 2 additional threads and all 3 threads// then run simultaneously without any synchronization.  No data// is shared between the threads.// We instantiate an object of the ThreadX class. Next we will// create a thread and specify that the thread is to begin executing// the function ThreadEntryPoint() on object o1. Once started,// this thread will execute until that function terminates or// until the overall process terminates.ThreadX * o1 = new ThreadX( 0, 1, 2000 );// When developing a multithreaded WIN32-based application with// Visual C++, you need to use the CRT thread functions to create// any threads that call CRT functions. Hence to create and terminate// threads, use _beginthreadex() and _endthreadex() instead of// the Win32 APIs CreateThread() and EndThread().// The multithread library LIBCMT.LIB includes the _beginthread()// and _endthread() functions. The _beginthread() function performs// initialization without which many C run-time functions will fail.// You must use _beginthread() instead of CreateThread() in C programs// built with LIBCMT.LIB if you intend to call C run-time functions.// Unlike the thread handle returned by _beginthread(), the thread handle// returned by _beginthreadex() can be used with the synchronization APIs.HANDLE   hth1;unsigned  uiThread1ID;hth1 = (HANDLE)_beginthreadex( NULL,         // security0,            // stack sizeThreadX::ThreadStaticEntryPoint,o1,           // arg listCREATE_SUSPENDED,  // so we can later call ResumeThread()&uiThread1ID );if ( hth1 == 0 )printf("Failed to create thread 1\n");DWORD   dwExitCode;GetExitCodeThread( hth1, &dwExitCode );  // should be STILL_ACTIVE = 0x00000103 = 259printf( "initial thread 1 exit code = %u\n", dwExitCode );// The System::Threading::Thread object in C++/CLI has a "Name" property.// To create the equivalent functionality in C++ I added a public data member// named threadName.o1->threadName = "t1";ThreadX * o2 = new ThreadX( -1000000, 0, 2000 );HANDLE   hth2;unsigned  uiThread2ID;hth2 = (HANDLE)_beginthreadex( NULL,         // security0,            // stack sizeThreadX::ThreadStaticEntryPoint,o2,           // arg listCREATE_SUSPENDED,  // so we can later call ResumeThread()&uiThread2ID );if ( hth2 == 0 )printf("Failed to create thread 2\n");GetExitCodeThread( hth2, &dwExitCode );  // should be STILL_ACTIVE = 0x00000103 = 259printf( "initial thread 2 exit code = %u\n", dwExitCode );o2->threadName = "t2";// If we hadn't specified CREATE_SUSPENDED in the call to _beginthreadex()// we wouldn't now need to call ResumeThread().ResumeThread( hth1 );   // serves the purpose of Jaeschke's t1->Start()ResumeThread( hth2 );// In C++/CLI the process continues until the last thread exits.// That is, the thread's have independent lifetimes. Hence// Jaeschke's original code was designed to show that the primary// thread could exit and not influence the other threads.// However in C++ the process terminates when the primary thread exits// and when the process terminates all its threads are then terminated.// Hence if you comment out the following waits, the non-primary// threads will never get a chance to run.WaitForSingleObject( hth1, INFINITE );WaitForSingleObject( hth2, INFINITE );GetExitCodeThread( hth1, &dwExitCode );printf( "thread 1 exited with code %u\n", dwExitCode );GetExitCodeThread( hth2, &dwExitCode );printf( "thread 2 exited with code %u\n", dwExitCode );// The handle returned by _beginthreadex() has to be closed// by the caller of _beginthreadex().CloseHandle( hth1 );CloseHandle( hth2 );delete o1;o1 = NULL;delete o2;o2 = NULL;printf("Primary thread terminating.\n");
}

二、解释

1.如果你正在编写C/C++代码，决不应该调用CreateThread。相反，应该使用VisualC++运行期库函数_beginthreadex，推出也应该使用_endthreadex。如果不使用Microsoft的VisualC++编译器，你的编译器供应商有它自己的CreateThred替代函数。不管这个替代函数是什么，你都必须使用。

2.因为_beginthreadex和_endthreadex是CRT线程函数，所以必须注意编译选项runtimelibaray的选择，使用MT或MTD。

3._beginthreadex函数的参数列表与CreateThread函数的参数列表是相同的，但是参数名和类型并不完全相同。这是因为Microsoft的C/C++运行期库的开发小组认为，C/C++运行期函数不应该对Windows数据类型有任何依赖。_beginthreadex函数也像CreateThread那样，返回新创建的线程的句柄。
下面是关于_beginthreadex的一些要点：

每个线程均获得由C/C++运行期库的堆栈分配的自己的tiddata内存结构。（tiddata结构位于Mtdll.h文件中的VisualC++源代码中）。

传递给_beginthreadex的线程函数的地址保存在tiddata内存块中。传递给该函数的参数也保存在该数据块中。

_beginthreadex确实从内部调用CreateThread，因为这是操作系统了解如何创建新线程的唯一方法。

当调用CreatetThread时，它被告知通过调用_threadstartex而不是pfnStartAddr来启动执行新线程。还有，传递给线程函数的参数是tiddata结构而不是pvParam的地址。

如果一切顺利，就会像CreateThread那样返回线程句柄。如果任何操作失败了，便返回NULL。

4._endthreadex的一些要点：

C运行期库的_getptd函数内部调用操作系统的TlsGetValue函数，该函数负责检索调用线程的tiddata内存块的地址。

然后该数据块被释放，而操作系统的ExitThread函数被调用，以便真正撤消该线程。当然，退出代码要正确地设置和传递。

5.虽然也提供了简化版的的_beginthread和_endthread，但是可控制性太差，所以一般不使用。

6.线程handle因为是内核对象，所以需要在最后closehandle。

7.更多的API：

HANDLE GetCurrentProcess();

HANDLE GetCurrentThread();

DWORD GetCurrentProcessId();

DWORD GetCurrentThreadId()；

DWORD SetThreadIdealProcessor(HANDLE hThread,DWORD dwIdealProcessor);

BOOL SetThreadPriority(HANDLE hThread,int nPriority);

BOOL SetPriorityClass(GetCurrentProcess(), IDLE_PRIORITY_CLASS);

BOOL GetThreadContext(HANDLE hThread,PCONTEXT pContext);

BOOL SwitchToThread();

三、注意

C++主线程的终止，同时也会终止所有主线程创建的子线程，不管子线程有没有执行完毕。所以上面的代码中如果不调用WaitForSingleObject，则2个子线程t1和t2可能并没有执行完毕或根本没有执行。

如果某线程挂起，然后有调用WaitForSingleObject等待该线程，就会导致死锁。所以上面的代码如果不调用ResumeThread，则会死锁。

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_beginthreadex创建多线程的用法

一、实例

二、解释

三、注意

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